Monitoring Patient Respiratory Effort During Mechanical Ventilation: Lung and Diaphragm-Protective Ventilation

Abstract

During assisted mechanical ventilation, spontaneous inspiratory effort can cause both lung (patient self-inflicted lung injury [P-SILI]) and diaphragm injury. While clinicians are primarily focused on monitoring lung function to prevent ventilator-induced lung injury (VILI) during passive mechanical ventilation, less attention may be paid to the risk of baro-volutrauma and myotrauma during assisted mechanical ventilation. During spontaneous breathing, the transpulmonary pressure can increase above a “safe limit.” Such excessive pressures are “unseen” when relying on the ventilator airway pressure waveform. The improper use of assisted mechanical ventilation (under-over ventilator assistance and severe forms of asynchronies) could lead to diaphragm weakness; a description of these mechanisms of lung and diaphragm injury are summarized in this chapter. Close respiratory monitoring is the key; safe spontaneous breathing presents a complex challenge because one must aim to minimize transpulmonary pressure while also maintaining an appropriate level of patient respiratory effort to achieve so-called “lung and diaphragm protective ventilation.” Several practical methods are available for monitoring patient respiratory effort during assisted mechanical ventilation; this review describes their use, meaning, and possible targets for safe inspiratory effort in clinical practice. Clinicians should strive to be aware of patient respiratory effort and appreciate the potential benefits and harms of manipulating respiratory effort during acute respiratory failure; the interpretation and application of measurements must always be guided by the clinical context.